Di tetrahydro furfuryl amines and preparation thereof



Patented July 14, 1936 oFFieE DI TETRAHYDRO FURFURYL AMINES ANDPREPARATION THEREOF No Drawing. Application April 4, 1934, Serial No.719,039

17 Claims.

This invention relates to certain new chemical compounds and to theprocess of their preparation.

' Heretofore it has been observed that when hydrofuramide, or, as it issometimes called, tri alpha furfurylidene diamine, is treated withhydrogen in the presence of an active catalyst, under superatmosphericpressures and at'temperatures in the neighborhood of 80-100 C. twowater-white liquids form; namely, tetrahydro alpha furfuryl amine,boiling at 150-152 C. at 735 mm. pressure, and di alpha furfuryl amine,boiling at 103-106 C. at 2-3 mm. pressure. Substantially quantitativeyields of these two products may be obtained in from one to two hours.

. This invention resides in the discovery that by hydrogenating difurfuryl amine, the compound di tetrahydro furfuryl amine is obtained.'Because of the presence of small amounts of impurities in hydrofuramidewhich tend to poison the catalyst and prevent the further reduction ofthe intermediate product, di furfuryl amine, it is desirable tosegregate the original products of the hydrogenation of hydrofuramideand afterwards hydrogenate di furfuryl amine in an additional step.

If di' furfuryl amine is segregated from the original hydrogenationproducts of hydrofur a amide and then hydrogenated separately, it may beefficiently converted to di tetrahydro furfuryl amine by subjecting itto a hydrogen pressure upwards of 20 atmospheres, preferably in theneighborhood of 125 atmospheres, and to a temperature upwards of 85 C.in the presence of a hydrogenation catalyst. Much higher pressures, forexample in the neighborhood of 400 atmospheres, may be employed, theiruse depending somewhat on the strength of the apparatus. Generallythereis little, if any, reduction of the di furfuryl amine at a temperaturebelow 120 C. At temperatures in the neighborhood of 140-150 0., the rateof reduction is rapid.

Although any hydrogenation catalyst is applicable for the purpose ofthis invention, it has beenfoun'd that'a supported nickel catalystprepared according to the process outlined more fully in the patentapplication of Homer Adkins, Serial No. 616,093, filed June 8, 1932,gives excellentresults. This catalyst is prepared by mixing an aqueoussolution of a nickel salt and a foraminous carrier, preferablyacid-washed kieselguhr, and thereafter grinding the carrier-nickel saltmixture until it is of a cream-like consistency. Following this, acarbonate precipitant which reacts basic to litmus paper, preferably anaqueous solution of an ammonium or alkali metal carbonate such asammonium carbonate, sodium carbonate or sodium bicarbonate, is added tothe mixture. After washing and drying, the resulting precipitated nickelcarbonate is reduced in a stream of hydrogen or other reducing gas forapproximately 60 to 80 minutes at 425475" 0., the finished catalystcontaining 14-15% nickel. Other catalysts prepared in a similar mannermay be used with excellent results, examples being those of copper andcobalt.

Platinum and other noble metal catalysts may be employed with excellentresults, but because of the lower cost of the base metal hydrogenationcatalysts, the latter will generally be found more desirable.

Nickel catalysts prepared by methods such as the following may be usedto advantage: (1) the reduction of any nickel salt, either supported orunsupported, by hydrogen or other reducing agent; (2) the treatment of anickel alloy such as nickel-aluminum or nickel-silicon with aqueousalkalis, particularly as described in United States Patent No. 1,628,190to Murray Raney; (3) the reduction of nickel salts in admixture withsalts of other metals of Groups VIII or I of Mendelejefis PeriodicTable, thereduced salts acting as co-catalysts; (4) the reduction ofnickel salts mixed with promoters such as oxides of the metals of GroupsII, III, IV, V, and VI of Mendelejeffs Periodic Table; (5) mechanicalsubdivision oi massive nickel; (6) anodic oxidation of nickel surfacesfollowed by reduction; (7) colloidal dispersion of metallic nickel; (8)precipitation by more electropositive metals such as aluminum and zinc.7

, In the hydrogenation of hydrofuramide, the compounds mono alphafurfuryl amine and di alpha furfuryl amine are first obtained but, sincemono alpha furfuryl amine is very easily reduced, it is converted almostinstantly to mono tetrahydro alpha furfuryl amine. The reduction of thedi alpha furfuryl amine is much more diflicult, and it should besegregated and separately reduced. The equations representing thevariable that the major portion of Fractions #2 and ous' reactions arebelieved to be as follows: #4 was also di tetrahydro furfuryl amine. In.

HC-CH 11(3 L-4:41

110-011 N at"; ("3 I 7 110-011 HO-C nc-on o H+3Hz Ht; (LJJ-NHa m": (LoeiI 511 O I l: 0 Ila 1 b \O no-cn N EH") -Hl-H l2Hz i413:

HaC-CH2 HzC-CH2 HzO'-C Hg 11 V g H H H H20 OO-NH2 H1O C Cl TC O CH2 0 Hz0 Hz l iz O The following examples are illustrative of the practice ofthe invention;

7 Example 1 ported on kieselguhr, prepared as described in Adkinsapplication Serial No. 616,093, filed June 8, 1932, are placed in asuitable hydrogenation bomb equipped soas to permit continuous agitationof its contents during the reaction. Hydrogen is admitted under aninitial pressure of approximately 125 atmospheres. V

The bomb is then heated, the temperature being'brought up to about 115C. during the first half hour, during which time little or no hydrogenabsorption occurs. Thereupon the temperature rises to 130 C. almost at'once, indicating that hydrogenation has begun, and'the external heatsupply is cut off. The absorption of hydrogen soon becomes very rapid,the temperature rising to about 150 C. within the space of a few minutesand remaining in the neighborhood of 150 C. for'approximately 80minutes. The reaction is then terminated, as the absorption of hydrogenby this time has practically, stopped.

;The equation representing the reaction is believed to be as follows:

; Threeother portions of di alpha furfuryl amine werehydrogenated-similarly and the products of all-four-runs,- after beingwashed with ether to obtained:

remove the catalyst, were combined, and fractionally distilled. I Thefollowing fractions were c. at in C. at 1-3 identifying fraction #3 asdiftetrahydro alpha furfuryl amine, a number of tests were made. First,a specific gravity test of Fraction #3 gave figures of 1.0334 at 15 C.and 1.0392 at 20 C. Next, 3.2 gram portion of Fraction #3 upon beingmixed with 5 grams of picric acid in 15 cc. of 2B alcoholgave a solutionfrom which a viscous oil a formed on chilling. The mixture upon standingovernight formed no crystals. The. flasl; containing the mixture wasthen placed in afreezing mixture,-after which the alcohol layer wasdecanted from the oily layer and the latter stirred in the cold. In fiveminutes a yellow solid, melting at 95 C., formed. This solid, upon beingrecrystallized from Water,'melted at 99-100 0'. Upon being furtherpurified by recrystallization from benzene and methyl alcohol, crystalsmelting at 102 103 C. and identified as di tetrahydro Y 7 of 13.44% fordi tetrahydro alpha furfuryl amine.

Example 2 Di alpha furfuryl amine in the amount of 92 grams washydrogenated under an initial pressure of approximately atmospheres ofhydrogen in the presence of 3 grams of a reduced nickel catalystsupported on kieselguhr. At 120 C., hydrogen absorption was firstobserved. At: C., the'absorption became so rapid that the temperature'of the reaction mixture rose to 198 C. in 5 minutes because of the heatevolved in the reaction. I The temperature, of the mixture was thenpermitted to fall to C., whereupon the experiment was stopped. 'Theproduct after being washed with .ether to remove the catalyst andfiltered was fractionally distilled,the following fractions beingobtained:

#1-upto 119 C. at 7.5 mm.etherwashings. #2119- 120 C. at 7.5 mm.89.2grams of di tetrahydro alpha furfuryl amine.

,#3'above 120 C. ,at 7 .5 mm.-'1-.7 grams of vapors condensedfromfractionating column. Fraction #2 was ,a water white liquid ofcharacteristic odor and gave a picrate-from alcohol melting at 104-105C. -The picrate, upon, being analyzed byprecipitating picric acid asnitron picrate and weighing, gave a picric acid analysis of 55.37% ascompared with the theoretical content of 55.32% for di tetrahydrofurfuryl amine picrate.

The examples hereinbefore set forth are to be understood as illustrativeonly and not as limitative of the scope of the invention. For example,other hydrogenation catalysts than those indicated in the examples maybe employed. While the invention has been described in detail inconnection with its application to the alpha furfuryl amines, it is tobe understood that the beta furfuryl amines may be prepared similarly bystarting with the beta furfuraldehyde in preparing the hydrofuramiderather than with the more readily available alpha furfuraldehyde,commonly called furfural. It is intended that the patent shall cover, bysuitable expression in the appended claims, whatever feautres ofpatentable novelty reside in the invention.

What I claim is:

l. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at superatmospheric pressure, at atemperature upwards of C. but below the temperature at which di furfurylamine decomposes, and in the presence of a hydrogenation catalyst.

2. The process of preparing di tethahydro furfuryl amine which compriseshydrogenating di furfuryl amine at a pressure of from 20 to 400atmospheres, at a temperature ranging from approximately 85 toapproximately 200 C., and in the presence of a hydrogenation catalyst.

3. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at superatmospheric pressure, at atemperature upwards of 85 C. but below the temperature at which difurfuryl amine decomposes, and in the presence of a base metalhydrogenation catalyst.

4. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at superatmospheric pressure, at atemperature upwards of 85 C. but below the temperature at which difurfuryl amine decomposes, and in the presence of a nickel catalyst.

5. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at superatmospheric pressure, at atemperature upwards of 85 C. but below the temperature at which difurfuryl amine decomposes, and in the presence of a reduced nickelcatalyst.

6. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at superatmospheric pressure, at atemperature upwards of C. but below the temperature at which di furfurylamine decomposes, and in the presence of a reduced nickelcatalystsupported on kieselguhr.

'7. The process of preparing di tetrahydro furfuryl amine whichcomprises hydrogenating di furfuryl amine at superatmospheric pressure,at a temperature upwards of 120 C. but below the temperature at which difurfuryl amine decomposes, and in the presence of a supported nickelcatalyst.

8. The process of preparing di tertahydro furfuryl amine which compriseshydrogenating di furfuryl amine at a pressure of from 20 to 400atmospheres, at a temperature ranging from approximately 85 toapproximately 200 C., and in the presence of a base metal hydrogenationcatalyst.

9. The process of preparing di tetrahydro furfuryl amine which compriseshydrogenating di furfuryl amine at a pressure of from 20 to 200atmospheres, at a temperature ranging from approximately 85 toapproximately 200 C., and in the presence of a nickel catalyst.

10. The process of preparing di tetrahydro furfuryl amine whichcomprises hydrogenating di furfuryl amine at a pressure of from 20 to200 atmospheres, at a temperature ranging from approximately 120 toapproximately 200 C., and in the presence of a reduced nickel catalyst.

11. The process of preparing di tetrahydro fur-- 4 furyl amine whichcomprises hydrogenating di furfuryl amine at a pressure of from 20 to200 atmospheres, at a temperature ranging from approximately 120 to 200C., and in the presence of a reduced nickel catalyst supported onkieselguhr.

12. The process of preparing di tetrahydro furiuryl amine whichcomprises hydrogenating dl furfuryl amine at a pressure of from 20 to200 atmospheres, at a temperature ranging from approximately 120 toapproximately 200 C., and in the presence of a supported nickelcatalyst.

13. The process of preparing di tetrahydro alpha furfuryl amine whichcomprises treating di alpha furfuryl amine with hydrogen at an initialpressure in the neighborhood of atmospheres, at a temperature in theneighborhood of -150 C. and in the presence of a hydrogenation catalyst.

14. The process of preparing di tetrahydro alpha furfuryl amine whichcomprises treating di alpha furfuryl amine with hydrogen at an initialpressure in the neighborhood of 125 atmospheres,

at a temperature in the neighborhood of C. and in the presence of asupported nickel catalyst.

15. The process of preparing di tetrahydro furfuryl amine whichcomprises treating hydrofuramide with hydrogen under reducingconditions, segregating from the resulting product di furfuryl amine,and hydrogenating the di furfuryl amine under superatmospheric pressure,in the presence of a hydrogenation catalyst and at a temperature upwardsof 120 C. but below the temperature at which di furfuryl aminedecomposes.

16. As a new compound, di tetrahydro furfuryl amine.

1'7. As a new compound, di tetrahydro alpha furfuryl amine.

HOWARD I. CRAMER.

